1. Field of the Invention
This invention relates to an apparatus for handling tape, and more particularly, to an apparatus for handling tape in a postage meter type printing machine.
2. Description of Prior Art
This invention is an improvement to U.S. Pat. No. 3,791,293 assigned to the assignee of the instant invention and said patent is incorporated by reference into this specification. U.S. Pat. No. 3,791,293 discloses a flatbed printing machine of the postage meter type which can print selectively on letters or on a tape, which in the case of the latter, can be adhered either to an envelope or a parcel. A composite tape is used when the machine is in its tape mode.
The composite tape comprises a print receiving first strip which has a backing of pressure sensitive adhesive. This strip is divided into units of equal length by perforations defining lines of tear across the tape. A protective second strip is adapted to overlie the adhesive backing of the first strip. The protective second strip extends laterally beyond the first strip along one edge. The extended edge portion of the second strip is slotted with slots, or perforations, the midpoints of which, are spaced apart the same distance as the lines of tear in the first strip and are aligned with the lines of tear in the first strip.
The composite tape is threaded through the postage meter printing machine so that an impression can be formed during each print operation on either one or two units of equal length of the first strip of the tape, each unit being defined by the lines of tear across the tape. As the tape is threaded through the postage meter type printing apparatus the tape is advanced from a source of supply such as a tape roll mounted on a first reel, over guide means, and a vertically reciprocable track, and at the outer end of the track the protective second strip is separated from the first strip and is led back and its free end is engaged with a second reel which is power-driven to wind up the second strip and thereby advance both strips. The free end of the print-receiving strip, which has been projected from one end of the machine, is torn off at a line of tear which disposed adjacent to point of separation between the two tape strips and also adjacent to the end of the machine, after each print operation.
With the tape threaded through the tape handling apparatus as described above and a postage meter properly assembled with it, a label printing and advancing operation is initiated by the operator depressing a key of the postage meter thus actuating its platen and elevating the tape track bringing the tape which is on the track into contact with the printing head which is within the postage meter.
In falling back to its lower position, the tape supporting track causes actuation of a switch which turns on a motor. The rotation of the motor shaft turns the reel on which the protective second strip is wound up, also unwinding the composite tape from a tape supply reel and advancing it a predetermined distance through the guide means and over the track.
Adjacent the take-up reel, a star wheel is rotated by the advancing protective second tape strip which initially is the underply of the aforementioned two-ply tape strip. The star wheel is described in detail in U.S. Pat. No. 3,712,527, assigned to the same assignee as the present invention, and said patent is incorporated be reference into this specification.
The star wheel has peripheral radial projections that are engaged in the slots or perforations along the extended edge portion of the second strip or the underply protective backing of the two-ply strip, and a predetermined number of circularly disposed contact pins projecting from its rear surface, the spacing between the pins being determinative of the length of the tape advance. The star wheel is rotated through meshing engagement of the slots in the advancing tape with the peripheral radial projections on the star wheel, as the tape is advanced. The contact pins projecting from the star wheel are used either through an intermediate member or directly to strike and raise the switch arm of the switch controlling the motor advancing the tape take-up reel, thus deactuating the motor and stopping the travel of the tape after each advance of a distance equal to the length of either one or two predetermined units of the tape strip. As shown in U.S. Pat. No. 3,712,527, the contact pins can directly strike the switch arm, or as in U.S. Pat. No. 3,791,293, the pins can be used to activate a segmental cam through a linkage of a series of interacting members to strike the switch arm. Depending upon the number of pins which are manually projected from the rear surface of the star wheel, as shown in said U.S. Pat. No. 3,712,527, the motor on the take-up reel is deactuated after an advance of the tape a distance equal to the length of one or two units, as desired, after each print operation.
In the printing device illustrated in U.S. Pat. No. 3,791,293, the tape which advances the star wheel is wrapped around the star wheel circumference for an appreciable length so that the tape not only drives the star wheel through the meshing engagement of its radial projections and the slots in the tape, but by the frictional engagement of the surface of the tape itself with the cylindrical surface of the star wheel. If for some reason, the slots in the edge of the tape become mis-aligned (out of time) with a radial projection on the star wheel, the star wheel projection could puncture the tape creating its own slot which in turn will cause rotation of the wheel and its pin contacts during successive print operations to prematurely deactuate the tape drive or slippage may occur between the frictional engagement of the wheel and tape without the projections on the wheel being aligned with the slots in the tape, which will result in too little or too much tape being presented to the operator in advance or in arrears of the tear line. Furthermore, if a radial projection on the star wheel makes contact with the tape as it is advanced before entering a slot in the tape edge, the tape can break, necessitating rethreading of the tape in the machine.